Hypertension Linked to Thinking Problems in Middle Age

Aug. 25 -- MONDAY, Aug. 24 (HealthDay News) -- High blood pressure is linked to loss of mental function in people over 45, a new study finds.

"A number of other studies have looked at the relationship between blood pressure and cognitive function," said George Howard, chairman of the department of biostatistics at the University of Alabama at Birmingham School of Public Health, and a member of the team reporting the finding in the Aug. 25 issue of Neurology. "Some studies found such a relationship, others did not. We think that this study, one of the larger ones and well done, adds substantially to whether there is a relationship here."

Specifically, the study found that every 10-point increase in diastolic blood pressure (the bottom number in the blood pressure reading), increased the odds of having some impairment in thinking ability by 7 percent.

It's not clear why diastolic pressure, taken while the heart is relaxing, should be associated with mental ability, Howard said.

"One idea is that diastolic pressure is tightly tied to small blood vessel disease and perfusion pressure," he said. Perfusion pressure is the force by which blood spreads through vessels of the brain. "Another idea is that people with high systolic pressure tend to die. Once they are dead, they cannot be part of our study."

That study is aimed at determining why blacks, and Southerners in general, are more likely to die of strokes than other Americans. The Reasons for Geographic and Racial Differences in Stroke Study has been following nearly 20,000 people 45 and older for years.

Data for the Neurology report was extracted from the overall study by Dr. Georgios Tsivgoulis, a neurologist who divides his time between the University of Alabama and Greece.

While the 7 percent increase in cognitive problems found in the study might seem small, "changing a modest amount can have a huge impact because of the large number of people involved," Howard said. Just under half of all of the study participants are taking medications to control high blood pressure.